Abstract: The migration and clogging of fine particles in porous media with seepage are of great significance for preventing the internal erosion of soils and improving the performance of artificial filtration facilities. The migration and clogging in the gravel substrate under the seepage are studied based on the X-CT technology. The results indicate that the migration of particles in porous media generally increases with the increase of seepage velocity, and its influence is significantly different under different particle size ratios. The X-CT results indicate that the particles present a stable vertical distribution in the column and clogging formed under the smaller d_ss/d_fs. However, the vertical accumulative interception curve of particles presents a linear distribution and changes continuously, indicating that the particles penetrate continuously under the higher d_ss/d_fs. On this basis, the threshold whether particles penetrating or clogging is determined. Moreover, the factor of \text(d_\textss\text/d_\textfs\text)^2.1Re^*1.8(tu^*/H)^0.2 is the best dimensionless parameter for calculating the penetration rate of particles, and the relevant formula is developed.